/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_correlate_fast_q15.c
*
* Description:	Fast Q15 Correlation.
*
* Target Processor: Cortex-M4/Cortex-M3
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.11 2011/10/18
*    Bug Fix in conv, correlation, partial convolution.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupFilters
 */

/**
 * @addtogroup Corr
 * @{
 */

/**
 * @brief Correlation of Q15 sequences (fast version) for Cortex-M3 and Cortex-M4.
 * @param[in] *pSrcA points to the first input sequence.
 * @param[in] srcALen length of the first input sequence.
 * @param[in] *pSrcB points to the second input sequence.
 * @param[in] srcBLen length of the second input sequence.
 * @param[out] *pDst points to the location where the output result is written.  Length 2 * max(srcALen, srcBLen) - 1.
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 *
 * \par
 * This fast version uses a 32-bit accumulator with 2.30 format.
 * The accumulator maintains full precision of the intermediate multiplication results but provides only a single guard bit.
 * There is no saturation on intermediate additions.
 * Thus, if the accumulator overflows it wraps around and distorts the result.
 * The input signals should be scaled down to avoid intermediate overflows.
 * Scale down one of the inputs by 1/min(srcALen, srcBLen) to avoid overflow since a
 * maximum of min(srcALen, srcBLen) number of additions is carried internally.
 * The 2.30 accumulator is right shifted by 15 bits and then saturated to 1.15 format to yield the final result.
 *
 * \par
 * See <code>arm_correlate_q15()</code> for a slower implementation of this function which uses a 64-bit accumulator to avoid wrap around distortion.
 */

void arm_correlate_fast_q15(
    q15_t* pSrcA,
    uint32_t srcALen,
    q15_t* pSrcB,
    uint32_t srcBLen,
    q15_t* pDst)
{
#ifndef UNALIGNED_SUPPORT_DISABLE

	q15_t* pIn1;                                   /* inputA pointer               */
	q15_t* pIn2;                                   /* inputB pointer               */
	q15_t* pOut = pDst;                            /* output pointer               */
	q31_t sum, acc0, acc1, acc2, acc3;             /* Accumulators                  */
	q15_t* px;                                     /* Intermediate inputA pointer  */
	q15_t* py;                                     /* Intermediate inputB pointer  */
	q15_t* pSrc1;                                  /* Intermediate pointers        */
	q31_t x0, x1, x2, x3, c0;                      /* temporary variables for holding input and coefficient values */
	uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3;  /* loop counter                 */
	int32_t inc = 1;                               /* Destination address modifier */


	/* The algorithm implementation is based on the lengths of the inputs. */
	/* srcB is always made to slide across srcA. */
	/* So srcBLen is always considered as shorter or equal to srcALen */
	/* But CORR(x, y) is reverse of CORR(y, x) */
	/* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
	/* and the destination pointer modifier, inc is set to -1 */
	/* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */
	/* But to improve the performance,
	 * we include zeroes in the output instead of zero padding either of the the inputs*/
	/* If srcALen > srcBLen,
	 * (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */
	/* If srcALen < srcBLen,
	 * (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */
	if(srcALen >= srcBLen) {
		/* Initialization of inputA pointer */
		pIn1 = (pSrcA);

		/* Initialization of inputB pointer */
		pIn2 = (pSrcB);

		/* Number of output samples is calculated */
		outBlockSize = (2u * srcALen) - 1u;

		/* When srcALen > srcBLen, zero padding is done to srcB
		 * to make their lengths equal.
		 * Instead, (outBlockSize - (srcALen + srcBLen - 1))
		 * number of output samples are made zero */
		j = outBlockSize - (srcALen + (srcBLen - 1u));

		/* Updating the pointer position to non zero value */
		pOut += j;

	} else {
		/* Initialization of inputA pointer */
		pIn1 = (pSrcB);

		/* Initialization of inputB pointer */
		pIn2 = (pSrcA);

		/* srcBLen is always considered as shorter or equal to srcALen */
		j = srcBLen;
		srcBLen = srcALen;
		srcALen = j;

		/* CORR(x, y) = Reverse order(CORR(y, x)) */
		/* Hence set the destination pointer to point to the last output sample */
		pOut = pDst + ((srcALen + srcBLen) - 2u);

		/* Destination address modifier is set to -1 */
		inc = -1;

	}

	/* The function is internally
	 * divided into three parts according to the number of multiplications that has to be
	 * taken place between inputA samples and inputB samples. In the first part of the
	 * algorithm, the multiplications increase by one for every iteration.
	 * In the second part of the algorithm, srcBLen number of multiplications are done.
	 * In the third part of the algorithm, the multiplications decrease by one
	 * for every iteration.*/
	/* The algorithm is implemented in three stages.
	 * The loop counters of each stage is initiated here. */
	blockSize1 = srcBLen - 1u;
	blockSize2 = srcALen - (srcBLen - 1u);
	blockSize3 = blockSize1;

	/* --------------------------
	 * Initializations of stage1
	 * -------------------------*/

	/* sum = x[0] * y[srcBlen - 1]
	 * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1]
	 * ....
	 * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1]
	 */

	/* In this stage the MAC operations are increased by 1 for every iteration.
	   The count variable holds the number of MAC operations performed */
	count = 1u;

	/* Working pointer of inputA */
	px = pIn1;

	/* Working pointer of inputB */
	pSrc1 = pIn2 + (srcBLen - 1u);
	py = pSrc1;

	/* ------------------------
	 * Stage1 process
	 * ----------------------*/

	/* The first loop starts here */
	while(blockSize1 > 0u) {
		/* Accumulator is made zero for every iteration */
		sum = 0;

		/* Apply loop unrolling and compute 4 MACs simultaneously. */
		k = count >> 2;

		/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
		 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* x[0] * y[srcBLen - 4] , x[1] * y[srcBLen - 3] */
			sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);
			/* x[3] * y[srcBLen - 1] , x[2] * y[srcBLen - 2] */
			sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, compute any remaining MACs here.
		 ** No loop unrolling is used. */
		k = count % 0x4u;

		while(k > 0u) {
			/* Perform the multiply-accumulates */
			/* x[0] * y[srcBLen - 1] */
			sum = __SMLAD(*px++, *py++, sum);

			/* Decrement the loop counter */
			k--;
		}

		/* Store the result in the accumulator in the destination buffer. */
		*pOut = (q15_t)(sum >> 15);
		/* Destination pointer is updated according to the address modifier, inc */
		pOut += inc;

		/* Update the inputA and inputB pointers for next MAC calculation */
		py = pSrc1 - count;
		px = pIn1;

		/* Increment the MAC count */
		count++;

		/* Decrement the loop counter */
		blockSize1--;
	}

	/* --------------------------
	 * Initializations of stage2
	 * ------------------------*/

	/* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1]
	 * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1]
	 * ....
	 * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
	 */

	/* Working pointer of inputA */
	px = pIn1;

	/* Working pointer of inputB */
	py = pIn2;

	/* count is index by which the pointer pIn1 to be incremented */
	count = 0u;

	/* -------------------
	 * Stage2 process
	 * ------------------*/

	/* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
	 * So, to loop unroll over blockSize2,
	 * srcBLen should be greater than or equal to 4, to loop unroll the srcBLen loop */
	if(srcBLen >= 4u) {
		/* Loop unroll over blockSize2, by 4 */
		blkCnt = blockSize2 >> 2u;

		while(blkCnt > 0u) {
			/* Set all accumulators to zero */
			acc0 = 0;
			acc1 = 0;
			acc2 = 0;
			acc3 = 0;

			/* read x[0], x[1] samples */
			x0 = *__SIMD32(px);
			/* read x[1], x[2] samples */
			x1 = _SIMD32_OFFSET(px + 1);
			px += 2u;

			/* Apply loop unrolling and compute 4 MACs simultaneously. */
			k = srcBLen >> 2u;

			/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
			 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
			do {
				/* Read the first two inputB samples using SIMD:
				 * y[0] and y[1] */
				c0 = *__SIMD32(py)++;

				/* acc0 +=  x[0] * y[0] + x[1] * y[1] */
				acc0 = __SMLAD(x0, c0, acc0);

				/* acc1 +=  x[1] * y[0] + x[2] * y[1] */
				acc1 = __SMLAD(x1, c0, acc1);

				/* Read x[2], x[3] */
				x2 = *__SIMD32(px);

				/* Read x[3], x[4] */
				x3 = _SIMD32_OFFSET(px + 1);

				/* acc2 +=  x[2] * y[0] + x[3] * y[1] */
				acc2 = __SMLAD(x2, c0, acc2);

				/* acc3 +=  x[3] * y[0] + x[4] * y[1] */
				acc3 = __SMLAD(x3, c0, acc3);

				/* Read y[2] and y[3] */
				c0 = *__SIMD32(py)++;

				/* acc0 +=  x[2] * y[2] + x[3] * y[3] */
				acc0 = __SMLAD(x2, c0, acc0);

				/* acc1 +=  x[3] * y[2] + x[4] * y[3] */
				acc1 = __SMLAD(x3, c0, acc1);

				/* Read x[4], x[5] */
				x0 = _SIMD32_OFFSET(px + 2);

				/* Read x[5], x[6] */
				x1 = _SIMD32_OFFSET(px + 3);
				px += 4u;

				/* acc2 +=  x[4] * y[2] + x[5] * y[3] */
				acc2 = __SMLAD(x0, c0, acc2);

				/* acc3 +=  x[5] * y[2] + x[6] * y[3] */
				acc3 = __SMLAD(x1, c0, acc3);

			} while(--k);

			/* For the next MAC operations, SIMD is not used
			 * So, the 16 bit pointer if inputB, py is updated */

			/* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
			 ** No loop unrolling is used. */
			k = srcBLen % 0x4u;

			if(k == 1u) {
				/* Read y[4] */
				c0 = *py;
#ifdef  ARM_MATH_BIG_ENDIAN

				c0 = c0 << 16u;

#else

				c0 = c0 & 0x0000FFFF;

#endif /*      #ifdef  ARM_MATH_BIG_ENDIAN     */

				/* Read x[7] */
				x3 = *__SIMD32(px);
				px++;

				/* Perform the multiply-accumulates */
				acc0 = __SMLAD(x0, c0, acc0);
				acc1 = __SMLAD(x1, c0, acc1);
				acc2 = __SMLADX(x1, c0, acc2);
				acc3 = __SMLADX(x3, c0, acc3);
			}

			if(k == 2u) {
				/* Read y[4], y[5] */
				c0 = *__SIMD32(py);

				/* Read x[7], x[8] */
				x3 = *__SIMD32(px);

				/* Read x[9] */
				x2 = _SIMD32_OFFSET(px + 1);
				px += 2u;

				/* Perform the multiply-accumulates */
				acc0 = __SMLAD(x0, c0, acc0);
				acc1 = __SMLAD(x1, c0, acc1);
				acc2 = __SMLAD(x3, c0, acc2);
				acc3 = __SMLAD(x2, c0, acc3);
			}

			if(k == 3u) {
				/* Read y[4], y[5] */
				c0 = *__SIMD32(py)++;

				/* Read x[7], x[8] */
				x3 = *__SIMD32(px);

				/* Read x[9] */
				x2 = _SIMD32_OFFSET(px + 1);

				/* Perform the multiply-accumulates */
				acc0 = __SMLAD(x0, c0, acc0);
				acc1 = __SMLAD(x1, c0, acc1);
				acc2 = __SMLAD(x3, c0, acc2);
				acc3 = __SMLAD(x2, c0, acc3);

				c0 = (*py);
				/* Read y[6] */
#ifdef  ARM_MATH_BIG_ENDIAN

				c0 = c0 << 16u;
#else

				c0 = c0 & 0x0000FFFF;
#endif /*      #ifdef  ARM_MATH_BIG_ENDIAN     */

				/* Read x[10] */
				x3 = _SIMD32_OFFSET(px + 2);
				px += 3u;

				/* Perform the multiply-accumulates */
				acc0 = __SMLADX(x1, c0, acc0);
				acc1 = __SMLAD(x2, c0, acc1);
				acc2 = __SMLADX(x2, c0, acc2);
				acc3 = __SMLADX(x3, c0, acc3);
			}

			/* Store the result in the accumulator in the destination buffer. */
			*pOut = (q15_t)(acc0 >> 15);
			/* Destination pointer is updated according to the address modifier, inc */
			pOut += inc;

			*pOut = (q15_t)(acc1 >> 15);
			pOut += inc;

			*pOut = (q15_t)(acc2 >> 15);
			pOut += inc;

			*pOut = (q15_t)(acc3 >> 15);
			pOut += inc;

			/* Increment the pointer pIn1 index, count by 1 */
			count += 4u;

			/* Update the inputA and inputB pointers for next MAC calculation */
			px = pIn1 + count;
			py = pIn2;


			/* Decrement the loop counter */
			blkCnt--;
		}

		/* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
		 ** No loop unrolling is used. */
		blkCnt = blockSize2 % 0x4u;

		while(blkCnt > 0u) {
			/* Accumulator is made zero for every iteration */
			sum = 0;

			/* Apply loop unrolling and compute 4 MACs simultaneously. */
			k = srcBLen >> 2u;

			/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
			 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
			while(k > 0u) {
				/* Perform the multiply-accumulates */
				sum += ((q31_t) * px++ * *py++);
				sum += ((q31_t) * px++ * *py++);
				sum += ((q31_t) * px++ * *py++);
				sum += ((q31_t) * px++ * *py++);

				/* Decrement the loop counter */
				k--;
			}

			/* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
			 ** No loop unrolling is used. */
			k = srcBLen % 0x4u;

			while(k > 0u) {
				/* Perform the multiply-accumulates */
				sum += ((q31_t) * px++ * *py++);

				/* Decrement the loop counter */
				k--;
			}

			/* Store the result in the accumulator in the destination buffer. */
			*pOut = (q15_t)(sum >> 15);
			/* Destination pointer is updated according to the address modifier, inc */
			pOut += inc;

			/* Increment the pointer pIn1 index, count by 1 */
			count++;

			/* Update the inputA and inputB pointers for next MAC calculation */
			px = pIn1 + count;
			py = pIn2;

			/* Decrement the loop counter */
			blkCnt--;
		}
	} else {
		/* If the srcBLen is not a multiple of 4,
		 * the blockSize2 loop cannot be unrolled by 4 */
		blkCnt = blockSize2;

		while(blkCnt > 0u) {
			/* Accumulator is made zero for every iteration */
			sum = 0;

			/* Loop over srcBLen */
			k = srcBLen;

			while(k > 0u) {
				/* Perform the multiply-accumulate */
				sum += ((q31_t) * px++ * *py++);

				/* Decrement the loop counter */
				k--;
			}

			/* Store the result in the accumulator in the destination buffer. */
			*pOut = (q15_t)(sum >> 15);
			/* Destination pointer is updated according to the address modifier, inc */
			pOut += inc;

			/* Increment the MAC count */
			count++;

			/* Update the inputA and inputB pointers for next MAC calculation */
			px = pIn1 + count;
			py = pIn2;

			/* Decrement the loop counter */
			blkCnt--;
		}
	}

	/* --------------------------
	 * Initializations of stage3
	 * -------------------------*/

	/* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
	 * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
	 * ....
	 * sum +=  x[srcALen-2] * y[0] + x[srcALen-1] * y[1]
	 * sum +=  x[srcALen-1] * y[0]
	 */

	/* In this stage the MAC operations are decreased by 1 for every iteration.
	   The count variable holds the number of MAC operations performed */
	count = srcBLen - 1u;

	/* Working pointer of inputA */
	pSrc1 = (pIn1 + srcALen) - (srcBLen - 1u);
	px = pSrc1;

	/* Working pointer of inputB */
	py = pIn2;

	/* -------------------
	 * Stage3 process
	 * ------------------*/

	while(blockSize3 > 0u) {
		/* Accumulator is made zero for every iteration */
		sum = 0;

		/* Apply loop unrolling and compute 4 MACs simultaneously. */
		k = count >> 2u;

		/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
		 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* Perform the multiply-accumulates */
			/* sum += x[srcALen - srcBLen + 4] * y[3] , sum += x[srcALen - srcBLen + 3] * y[2] */
			sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);
			/* sum += x[srcALen - srcBLen + 2] * y[1] , sum += x[srcALen - srcBLen + 1] * y[0] */
			sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, compute any remaining MACs here.
		 ** No loop unrolling is used. */
		k = count % 0x4u;

		while(k > 0u) {
			/* Perform the multiply-accumulates */
			sum = __SMLAD(*px++, *py++, sum);

			/* Decrement the loop counter */
			k--;
		}

		/* Store the result in the accumulator in the destination buffer. */
		*pOut = (q15_t)(sum >> 15);
		/* Destination pointer is updated according to the address modifier, inc */
		pOut += inc;

		/* Update the inputA and inputB pointers for next MAC calculation */
		px = ++pSrc1;
		py = pIn2;

		/* Decrement the MAC count */
		count--;

		/* Decrement the loop counter */
		blockSize3--;
	}

#else

	q15_t* pIn1;                                   /* inputA pointer               */
	q15_t* pIn2;                                   /* inputB pointer               */
	q15_t* pOut = pDst;                            /* output pointer               */
	q31_t sum, acc0, acc1, acc2, acc3;             /* Accumulators                  */
	q15_t* px;                                     /* Intermediate inputA pointer  */
	q15_t* py;                                     /* Intermediate inputB pointer  */
	q15_t* pSrc1;                                  /* Intermediate pointers        */
	q31_t x0, x1, x2, x3, c0;                      /* temporary variables for holding input and coefficient values */
	uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3;  /* loop counter                 */
	int32_t inc = 1;                               /* Destination address modifier */
	q15_t a, b;


	/* The algorithm implementation is based on the lengths of the inputs. */
	/* srcB is always made to slide across srcA. */
	/* So srcBLen is always considered as shorter or equal to srcALen */
	/* But CORR(x, y) is reverse of CORR(y, x) */
	/* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
	/* and the destination pointer modifier, inc is set to -1 */
	/* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */
	/* But to improve the performance,
	 * we include zeroes in the output instead of zero padding either of the the inputs*/
	/* If srcALen > srcBLen,
	 * (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */
	/* If srcALen < srcBLen,
	 * (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */
	if(srcALen >= srcBLen) {
		/* Initialization of inputA pointer */
		pIn1 = (pSrcA);

		/* Initialization of inputB pointer */
		pIn2 = (pSrcB);

		/* Number of output samples is calculated */
		outBlockSize = (2u * srcALen) - 1u;

		/* When srcALen > srcBLen, zero padding is done to srcB
		 * to make their lengths equal.
		 * Instead, (outBlockSize - (srcALen + srcBLen - 1))
		 * number of output samples are made zero */
		j = outBlockSize - (srcALen + (srcBLen - 1u));

		/* Updating the pointer position to non zero value */
		pOut += j;

	} else {
		/* Initialization of inputA pointer */
		pIn1 = (pSrcB);

		/* Initialization of inputB pointer */
		pIn2 = (pSrcA);

		/* srcBLen is always considered as shorter or equal to srcALen */
		j = srcBLen;
		srcBLen = srcALen;
		srcALen = j;

		/* CORR(x, y) = Reverse order(CORR(y, x)) */
		/* Hence set the destination pointer to point to the last output sample */
		pOut = pDst + ((srcALen + srcBLen) - 2u);

		/* Destination address modifier is set to -1 */
		inc = -1;

	}

	/* The function is internally
	 * divided into three parts according to the number of multiplications that has to be
	 * taken place between inputA samples and inputB samples. In the first part of the
	 * algorithm, the multiplications increase by one for every iteration.
	 * In the second part of the algorithm, srcBLen number of multiplications are done.
	 * In the third part of the algorithm, the multiplications decrease by one
	 * for every iteration.*/
	/* The algorithm is implemented in three stages.
	 * The loop counters of each stage is initiated here. */
	blockSize1 = srcBLen - 1u;
	blockSize2 = srcALen - (srcBLen - 1u);
	blockSize3 = blockSize1;

	/* --------------------------
	 * Initializations of stage1
	 * -------------------------*/

	/* sum = x[0] * y[srcBlen - 1]
	 * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1]
	 * ....
	 * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1]
	 */

	/* In this stage the MAC operations are increased by 1 for every iteration.
	   The count variable holds the number of MAC operations performed */
	count = 1u;

	/* Working pointer of inputA */
	px = pIn1;

	/* Working pointer of inputB */
	pSrc1 = pIn2 + (srcBLen - 1u);
	py = pSrc1;

	/* ------------------------
	 * Stage1 process
	 * ----------------------*/

	/* The first loop starts here */
	while(blockSize1 > 0u) {
		/* Accumulator is made zero for every iteration */
		sum = 0;

		/* Apply loop unrolling and compute 4 MACs simultaneously. */
		k = count >> 2;

		/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
		 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* x[0] * y[srcBLen - 4] , x[1] * y[srcBLen - 3] */
			sum += ((q31_t) * px++ * *py++);
			sum += ((q31_t) * px++ * *py++);
			sum += ((q31_t) * px++ * *py++);
			sum += ((q31_t) * px++ * *py++);

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, compute any remaining MACs here.
		 ** No loop unrolling is used. */
		k = count % 0x4u;

		while(k > 0u) {
			/* Perform the multiply-accumulates */
			/* x[0] * y[srcBLen - 1] */
			sum += ((q31_t) * px++ * *py++);

			/* Decrement the loop counter */
			k--;
		}

		/* Store the result in the accumulator in the destination buffer. */
		*pOut = (q15_t)(sum >> 15);
		/* Destination pointer is updated according to the address modifier, inc */
		pOut += inc;

		/* Update the inputA and inputB pointers for next MAC calculation */
		py = pSrc1 - count;
		px = pIn1;

		/* Increment the MAC count */
		count++;

		/* Decrement the loop counter */
		blockSize1--;
	}

	/* --------------------------
	 * Initializations of stage2
	 * ------------------------*/

	/* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1]
	 * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1]
	 * ....
	 * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
	 */

	/* Working pointer of inputA */
	px = pIn1;

	/* Working pointer of inputB */
	py = pIn2;

	/* count is index by which the pointer pIn1 to be incremented */
	count = 0u;

	/* -------------------
	 * Stage2 process
	 * ------------------*/

	/* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
	 * So, to loop unroll over blockSize2,
	 * srcBLen should be greater than or equal to 4, to loop unroll the srcBLen loop */
	if(srcBLen >= 4u) {
		/* Loop unroll over blockSize2, by 4 */
		blkCnt = blockSize2 >> 2u;

		while(blkCnt > 0u) {
			/* Set all accumulators to zero */
			acc0 = 0;
			acc1 = 0;
			acc2 = 0;
			acc3 = 0;

			/* read x[0], x[1], x[2] samples */
			a = *px;
			b = *(px + 1);

#ifndef ARM_MATH_BIG_ENDIAN

			x0 = __PKHBT(a, b, 16);
			a = *(px + 2);
			x1 = __PKHBT(b, a, 16);

#else

			x0 = __PKHBT(b, a, 16);
			a = *(px + 2);
			x1 = __PKHBT(a, b, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

			px += 2u;

			/* Apply loop unrolling and compute 4 MACs simultaneously. */
			k = srcBLen >> 2u;

			/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
			 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
			do {
				/* Read the first two inputB samples using SIMD:
				 * y[0] and y[1] */
				a = *py;
				b = *(py + 1);

#ifndef ARM_MATH_BIG_ENDIAN

				c0 = __PKHBT(a, b, 16);

#else

				c0 = __PKHBT(b, a, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				/* acc0 +=  x[0] * y[0] + x[1] * y[1] */
				acc0 = __SMLAD(x0, c0, acc0);

				/* acc1 +=  x[1] * y[0] + x[2] * y[1] */
				acc1 = __SMLAD(x1, c0, acc1);

				/* Read x[2], x[3], x[4] */
				a = *px;
				b = *(px + 1);

#ifndef ARM_MATH_BIG_ENDIAN

				x2 = __PKHBT(a, b, 16);
				a = *(px + 2);
				x3 = __PKHBT(b, a, 16);

#else

				x2 = __PKHBT(b, a, 16);
				a = *(px + 2);
				x3 = __PKHBT(a, b, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				/* acc2 +=  x[2] * y[0] + x[3] * y[1] */
				acc2 = __SMLAD(x2, c0, acc2);

				/* acc3 +=  x[3] * y[0] + x[4] * y[1] */
				acc3 = __SMLAD(x3, c0, acc3);

				/* Read y[2] and y[3] */
				a = *(py + 2);
				b = *(py + 3);

				py += 4u;

#ifndef ARM_MATH_BIG_ENDIAN

				c0 = __PKHBT(a, b, 16);

#else

				c0 = __PKHBT(b, a, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				/* acc0 +=  x[2] * y[2] + x[3] * y[3] */
				acc0 = __SMLAD(x2, c0, acc0);

				/* acc1 +=  x[3] * y[2] + x[4] * y[3] */
				acc1 = __SMLAD(x3, c0, acc1);

				/* Read x[4], x[5], x[6] */
				a = *(px + 2);
				b = *(px + 3);

#ifndef ARM_MATH_BIG_ENDIAN

				x0 = __PKHBT(a, b, 16);
				a = *(px + 4);
				x1 = __PKHBT(b, a, 16);

#else

				x0 = __PKHBT(b, a, 16);
				a = *(px + 4);
				x1 = __PKHBT(a, b, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				px += 4u;

				/* acc2 +=  x[4] * y[2] + x[5] * y[3] */
				acc2 = __SMLAD(x0, c0, acc2);

				/* acc3 +=  x[5] * y[2] + x[6] * y[3] */
				acc3 = __SMLAD(x1, c0, acc3);

			} while(--k);

			/* For the next MAC operations, SIMD is not used
			 * So, the 16 bit pointer if inputB, py is updated */

			/* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
			 ** No loop unrolling is used. */
			k = srcBLen % 0x4u;

			if(k == 1u) {
				/* Read y[4] */
				c0 = *py;
#ifdef  ARM_MATH_BIG_ENDIAN

				c0 = c0 << 16u;

#else

				c0 = c0 & 0x0000FFFF;

#endif /*      #ifdef  ARM_MATH_BIG_ENDIAN     */

				/* Read x[7] */
				a = *px;
				b = *(px + 1);

				px++;;

#ifndef ARM_MATH_BIG_ENDIAN

				x3 = __PKHBT(a, b, 16);

#else

				x3 = __PKHBT(b, a, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				px++;

				/* Perform the multiply-accumulates */
				acc0 = __SMLAD(x0, c0, acc0);
				acc1 = __SMLAD(x1, c0, acc1);
				acc2 = __SMLADX(x1, c0, acc2);
				acc3 = __SMLADX(x3, c0, acc3);
			}

			if(k == 2u) {
				/* Read y[4], y[5] */
				a = *py;
				b = *(py + 1);

#ifndef ARM_MATH_BIG_ENDIAN

				c0 = __PKHBT(a, b, 16);

#else

				c0 = __PKHBT(b, a, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				/* Read x[7], x[8], x[9] */
				a = *px;
				b = *(px + 1);

#ifndef ARM_MATH_BIG_ENDIAN

				x3 = __PKHBT(a, b, 16);
				a = *(px + 2);
				x2 = __PKHBT(b, a, 16);

#else

				x3 = __PKHBT(b, a, 16);
				a = *(px + 2);
				x2 = __PKHBT(a, b, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				px += 2u;

				/* Perform the multiply-accumulates */
				acc0 = __SMLAD(x0, c0, acc0);
				acc1 = __SMLAD(x1, c0, acc1);
				acc2 = __SMLAD(x3, c0, acc2);
				acc3 = __SMLAD(x2, c0, acc3);
			}

			if(k == 3u) {
				/* Read y[4], y[5] */
				a = *py;
				b = *(py + 1);

#ifndef ARM_MATH_BIG_ENDIAN

				c0 = __PKHBT(a, b, 16);

#else

				c0 = __PKHBT(b, a, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				py += 2u;

				/* Read x[7], x[8], x[9] */
				a = *px;
				b = *(px + 1);

#ifndef ARM_MATH_BIG_ENDIAN

				x3 = __PKHBT(a, b, 16);
				a = *(px + 2);
				x2 = __PKHBT(b, a, 16);

#else

				x3 = __PKHBT(b, a, 16);
				a = *(px + 2);
				x2 = __PKHBT(a, b, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				/* Perform the multiply-accumulates */
				acc0 = __SMLAD(x0, c0, acc0);
				acc1 = __SMLAD(x1, c0, acc1);
				acc2 = __SMLAD(x3, c0, acc2);
				acc3 = __SMLAD(x2, c0, acc3);

				c0 = (*py);
				/* Read y[6] */
#ifdef  ARM_MATH_BIG_ENDIAN

				c0 = c0 << 16u;
#else

				c0 = c0 & 0x0000FFFF;
#endif /*      #ifdef  ARM_MATH_BIG_ENDIAN     */

				/* Read x[10] */
				b = *(px + 3);

#ifndef ARM_MATH_BIG_ENDIAN

				x3 = __PKHBT(a, b, 16);

#else

				x3 = __PKHBT(b, a, 16);

#endif	/*	#ifndef ARM_MATH_BIG_ENDIAN	*/

				px += 3u;

				/* Perform the multiply-accumulates */
				acc0 = __SMLADX(x1, c0, acc0);
				acc1 = __SMLAD(x2, c0, acc1);
				acc2 = __SMLADX(x2, c0, acc2);
				acc3 = __SMLADX(x3, c0, acc3);
			}

			/* Store the result in the accumulator in the destination buffer. */
			*pOut = (q15_t)(acc0 >> 15);
			/* Destination pointer is updated according to the address modifier, inc */
			pOut += inc;

			*pOut = (q15_t)(acc1 >> 15);
			pOut += inc;

			*pOut = (q15_t)(acc2 >> 15);
			pOut += inc;

			*pOut = (q15_t)(acc3 >> 15);
			pOut += inc;

			/* Increment the pointer pIn1 index, count by 1 */
			count += 4u;

			/* Update the inputA and inputB pointers for next MAC calculation */
			px = pIn1 + count;
			py = pIn2;


			/* Decrement the loop counter */
			blkCnt--;
		}

		/* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
		 ** No loop unrolling is used. */
		blkCnt = blockSize2 % 0x4u;

		while(blkCnt > 0u) {
			/* Accumulator is made zero for every iteration */
			sum = 0;

			/* Apply loop unrolling and compute 4 MACs simultaneously. */
			k = srcBLen >> 2u;

			/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
			 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
			while(k > 0u) {
				/* Perform the multiply-accumulates */
				sum += ((q31_t) * px++ * *py++);
				sum += ((q31_t) * px++ * *py++);
				sum += ((q31_t) * px++ * *py++);
				sum += ((q31_t) * px++ * *py++);

				/* Decrement the loop counter */
				k--;
			}

			/* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
			 ** No loop unrolling is used. */
			k = srcBLen % 0x4u;

			while(k > 0u) {
				/* Perform the multiply-accumulates */
				sum += ((q31_t) * px++ * *py++);

				/* Decrement the loop counter */
				k--;
			}

			/* Store the result in the accumulator in the destination buffer. */
			*pOut = (q15_t)(sum >> 15);
			/* Destination pointer is updated according to the address modifier, inc */
			pOut += inc;

			/* Increment the pointer pIn1 index, count by 1 */
			count++;

			/* Update the inputA and inputB pointers for next MAC calculation */
			px = pIn1 + count;
			py = pIn2;

			/* Decrement the loop counter */
			blkCnt--;
		}
	} else {
		/* If the srcBLen is not a multiple of 4,
		 * the blockSize2 loop cannot be unrolled by 4 */
		blkCnt = blockSize2;

		while(blkCnt > 0u) {
			/* Accumulator is made zero for every iteration */
			sum = 0;

			/* Loop over srcBLen */
			k = srcBLen;

			while(k > 0u) {
				/* Perform the multiply-accumulate */
				sum += ((q31_t) * px++ * *py++);

				/* Decrement the loop counter */
				k--;
			}

			/* Store the result in the accumulator in the destination buffer. */
			*pOut = (q15_t)(sum >> 15);
			/* Destination pointer is updated according to the address modifier, inc */
			pOut += inc;

			/* Increment the MAC count */
			count++;

			/* Update the inputA and inputB pointers for next MAC calculation */
			px = pIn1 + count;
			py = pIn2;

			/* Decrement the loop counter */
			blkCnt--;
		}
	}

	/* --------------------------
	 * Initializations of stage3
	 * -------------------------*/

	/* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
	 * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
	 * ....
	 * sum +=  x[srcALen-2] * y[0] + x[srcALen-1] * y[1]
	 * sum +=  x[srcALen-1] * y[0]
	 */

	/* In this stage the MAC operations are decreased by 1 for every iteration.
	   The count variable holds the number of MAC operations performed */
	count = srcBLen - 1u;

	/* Working pointer of inputA */
	pSrc1 = (pIn1 + srcALen) - (srcBLen - 1u);
	px = pSrc1;

	/* Working pointer of inputB */
	py = pIn2;

	/* -------------------
	 * Stage3 process
	 * ------------------*/

	while(blockSize3 > 0u) {
		/* Accumulator is made zero for every iteration */
		sum = 0;

		/* Apply loop unrolling and compute 4 MACs simultaneously. */
		k = count >> 2u;

		/* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
		 ** a second loop below computes MACs for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* Perform the multiply-accumulates */
			sum += ((q31_t) * px++ * *py++);
			sum += ((q31_t) * px++ * *py++);
			sum += ((q31_t) * px++ * *py++);
			sum += ((q31_t) * px++ * *py++);

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, compute any remaining MACs here.
		 ** No loop unrolling is used. */
		k = count % 0x4u;

		while(k > 0u) {
			/* Perform the multiply-accumulates */
			sum += ((q31_t) * px++ * *py++);

			/* Decrement the loop counter */
			k--;
		}

		/* Store the result in the accumulator in the destination buffer. */
		*pOut = (q15_t)(sum >> 15);
		/* Destination pointer is updated according to the address modifier, inc */
		pOut += inc;

		/* Update the inputA and inputB pointers for next MAC calculation */
		px = ++pSrc1;
		py = pIn2;

		/* Decrement the MAC count */
		count--;

		/* Decrement the loop counter */
		blockSize3--;
	}

#endif /*   #ifndef UNALIGNED_SUPPORT_DISABLE */

}

/**
 * @} end of Corr group
 */
